WO2014112821A1

WO2014112821A1 - Organic light-emitting diode

Info

Publication number: WO2014112821A1
Application number: PCT/KR2014/000498
Authority: WO
Inventors: 김장주; 김권현; 이성훈; 김세용
Original assignee: 서울대학교 산학협력단
Priority date: 2013-01-16
Filing date: 2014-01-16
Publication date: 2014-07-24
Also published as: KR101617877B1; KR20140092710A

Abstract

The present invention provides an organic light-emitting diode comprising a light-emitting layer which contains a dopant having improved horizontal orientation properties and employs a host/dopant system. One embodiment of the organic light-emitting diode according to one aspect of the present invention comprises: an anode layer; a light-emitting layer which is disposed on the anode layer and comprises a host comprising a hole transport material and an electron transport material, which form an exciplex, and a dopant comprising an Ir(mphmq)₂tmd-based phosphor; and a cathode layer disposed on the light-emitting layer.

Description

Organic light emitting diode

The present invention relates to an organic light emitting diode (OLED), and more particularly, to an organic light emitting diode employing an emission layer (EML) including a host and a phosphorescent dopant.

Organic light emitting diodes typically include a cathode layer, an electron transport layer, a light emitting layer, a hole transport layer and an anode layer, for example. In organic light emitting diodes, typically, the electron transporting layer, the light emitting layer, and the hole transporting layer are based on an organic compound. When a voltage is applied between the cathode layer and the anode layer, holes are injected from the anode layer through the hole transport layer into the light emitting layer. Electrons are injected from the cathode layer through the electron transport layer into the light emitting layer. Holes and electrons supplied to the light emitting layer recombine in the light emitting layer to form excitons. Excitons dissipate and release energy. The energy emitted from the exciton excites the light emitting material in the light emitting layer. The excited luminescent material changes to the ground state to generate light.

The light emitting material of the light emitting layer of the organic light emitting diode may be a fluorescent material excited by singlet excitons, or a phosphorescent material excited by triplet excitons. It is known that the ratio of the singlet excitons to triplet excitons in the light emitting layer is 1: 3. When the light emitting material present in the light emitting layer is a fluorescent material, triplet excitons do not contribute to the generation of light and are wasted. When the light emitting material present in the light emitting layer is a phosphor, both singlet excitons and triplet excitons may contribute to the generation of light, and thus the internal quantum efficiency of the light emitting layer may reach 100%.

The light emitting layer can include an undoped host. Alternatively, the light emitting layer may include a host and a dopant. The host acts as a matrix to form the physical form of the light emitting layer. Dopants are dispersed in the matrix. When the light emitting layer includes a undoped host, the host itself may be a light emitting material. When the light emitting layer includes a host and a dopant, the dopant may be a light emitting material, and the host may or may not be a light emitting material.

When the light emitting layer includes an undoped host, the host may form an excimer, whereby a decrease in color purity and a decrease in efficiency may occur. The light emitting layer including the host and the dopant has an improved color purity and an increase in efficiency through energy transfer, compared to the light emitting layer including the undoped host.

By employing a light emitting layer employing a phosphorescent material and employing a host / dopant method, the luminous efficiency of the organic light emitting diode has been increased. For example, some of the fabricated organic light emitting diodes have an external quantum efficiency of 29%. In particular, the external quantum efficiency of the red organic light emitting diode reached 26%. However, the luminous efficiency of the organic light emitting diode is still unsatisfactory.

The external quantum efficiency of the organic light emitting diode is determined by "external light efficiency x internal quantum efficiency x charge balance". Therefore, by increasing the external light efficiency of the light emitting layer, it is possible to improve the external quantum efficiency of the organic light emitting diode.

In the light emitting layer employing the host / dopant method, theoretical calculations show that the external light efficiency of the light emitting layer cannot exceed 30% unless the dopant is oriented in the host matrix. On the contrary, it is known that the external light efficiency of the light emitting layer can be increased to some extent if the dopant can be horizontally oriented in the host matrix. However, there is no case where a light emitting layer of a host / dopant method including a horizontally oriented dopant is implemented. Furthermore, there is no example of an organic light emitting diode device having an external quantum efficiency of 30% or more.

The present invention provides an organic light emitting diode comprising a light emitting layer of the host / dopant type containing a dopant having improved horizontal alignment.

One embodiment of the organic light emitting diode according to an aspect of the present invention,

An anode layer;

A light emitting layer on the anode layer, the light emitting layer including a dopant comprising a host including a hole transport material and an electron transport material and an Ir (mphmq) ₂ tmd phosphorescent material forming an exciplex; And

It includes; the cathode layer located on the light emitting layer.

According to the present invention, in the light emitting layer, when a hole transport material and an electron transport material forming an exciplex are used in combination as a host, and an Ir (mphmq) 2 tmd phosphorescent material is used as a dopant, The horizontal orientation of the dopant increases rapidly.

Although not limited to a specific mechanism, it is presumed to be due to the interaction between the Ir (mphmq) 2 tmd based phosphor and a host including the hole transport material and the electron transport material forming the exciplex. For example, the refractive index of the host including the NPB-based hole transport material and the B3PYMPM-based electron transport material forming the exciplex is optically anisotropic, and the Ir (mphmq) 2tmd-based phosphor exhibits an asymmetric chemical structure. . The refractive index of the host material having optical anisotropy means that the host material has an orientation in a particular direction. Thus, it is assumed that the orientation of the host material leads to the horizontal orientation of the dopant material. In addition, it is estimated that the horizontal orientation of the Ir (mphmq) 2tmd-based phosphor dopant is promoted by the asymmetry in the chemical structure of the Ir (mphmq) 2tmd-based phosphor dopant.

Since the horizontal alignment rate of the dopant in the light emitting layer of the present invention is very high, the light emitting layer of the present invention can exhibit much improved external light efficiency. Accordingly, the organic light emitting diode including the light emitting layer of the present invention can have a very improved external quantum efficiency.

1 is an emission spectrum of the organic light emitting diode of Example 1. FIG.

FIG. 2 is a measurement result of the horizontal alignment ratio of Ir (mphmq) ₂ tmd phosphor in the light emitting layer of the organic light emitting diode of Example 1. FIG.

3 is a measurement result of the horizontal orientation of the Ir (ppy) ₂ acac phosphor in the light emitting layer of the organic light emitting diode of Comparative Example 1.

4 is a relationship between voltage, current density, and light emission luminance of the organic light emitting diode of Example 1. FIG.

FIG. 5 is a relation between luminance and external quantum efficiency of the organic light emitting diode of Example 1. FIG.

FIG. 6 is a relation of power efficiency versus luminance for the organic light emitting diode of Example 1. FIG.

7 is a relationship between voltage, current density, and light emission luminance of the organic light emitting diode of Comparative Example 1. FIG.

8 is an external quantum efficiency and power efficiency of the organic light emitting diode of Comparative Example 1.

Hereinafter, an organic light emitting diode according to an aspect of the present invention will be described in more detail. One embodiment of the organic light emitting diode according to an aspect of the present invention,

An anode layer;

It includes; the cathode layer located on the light emitting layer.

Exiplex refers to an excited state charge transfer complex. In the present invention, the host of the light emitting layer includes a hole transport material and an electron transport material, the hole transport material and the electron transport material is a pair of materials forming an exciplex. Hole transport material: electron transport material pairs that form exciplexes include, but are not limited to, NPB: B3PYMPM, TCTA: B3PYMPM, TCTA: TPBi, TCTA: 3TPYMB, TCTA: BmPyPB, TCTA: BSFM, CBP: B3PYMPM, Or NPB: BSFM.

Ir (mphmq) ₂ tmd-based phosphor is Ir (mphmq) ₂ tmd (where mphmq = 2- (3,5-dimethylphenyl) -4-methylquinoline, tmd = 2,2,6,6-tetramethylheptane-3,5 -dionate) and derivatives thereof.

In the light emitting layer, when the content of the electron transport material is too small compared to the content of the hole transport material, the hole transport is relatively superior, whereas when the content of the electron transport material is too large relative to the content of the hole transport material, the electron transport property is superior.

In the light emitting layer, if the content of Ir (mphmq) ₂ tmd-based phosphor is too small, the efficiency can be reduced. In the light emitting layer, if the content of the Ir (mphmq) ₂ tmd-based phosphor is too large, dopant excitons may self extinguish themselves, thereby reducing efficiency.

For example, in the light emitting layer, the content of the electron transporting material may be about 50 mol parts to about 150 mol parts based on 100 mol parts of the hole transport material.

For example, in a light emitting layer, by the Ir (mphmq) ₂ content of tmd-based phosphors, based on the total weight of 100 wt% of the hole transport material, electron transport material and Ir (mphmq) ₂ tmd-based phosphor, about 1 wt% to about 20 wt%.

The ratio of the horizontally aligned transition dipoles of the dopant in the light emitting layer refers to the ratio of dopant molecules located in parallel with the main plane of the light emitting layer and the direction of the transition dipole among all the dopant molecules in the light emitting layer.

As the transition dipole moment of the dopant in the light emitting layer has a high horizontal orientation rate, the external light efficiency of the light emitting layer increases. Dopants with a vertically oriented dipole moment emit an electric field mainly in a direction perpendicular to the plane of the light emitting layer, whereby the emitted light is either a waveguide mode propagating into the light emitting layer and the transparent electrode layer or a surface plasmon polaritons with a metal electrode. Are mainly lost. In contrast, a dopant having a horizontally oriented dipole moment emits an electric field in a direction horizontal to the main plane of the light emitting layer, and the emitted light has a high rate of propagation outside the device. Therefore, as the ratio of the horizontally oriented transition dipole to the vertically oriented transition dipole is higher, the external light efficiency increases and the external quantum efficiency increases.

In the present invention, the horizontal orientation of the Ir (mphmq) ₂ tmd-based dopant in the light emitting layer is very high. In the host, when the dopant is randomly oriented, the horizontal orientation of the dopant is about 67%. According to the theoretical calculation, when the horizontal orientation of the dopant is about 67%, the external light efficiency of the light emitting layer is only about 25.7%. In contrast, in the light emitting layer of the present invention, the horizontal orientation of the Ir (mphmq) ₂ tmd-based dopant may be, for example, about 83% to about 89%. According to the theoretical calculation, when the horizontal orientation of the dopant is about 89%, the external light efficiency of the light emitting layer may have about 35.8%.

In the organic light emitting diode of the present invention, each of the anode layer and the cathode layer may be an opaque electrode, a transparent electrode, or a reflective electrode. In the operation of the organic light emitting diode of the present invention, a positive voltage is applied to the anode layer and a negative voltage is applied to the cathode layer. The opaque electrode may be, for example, alkali metals such as lithium, sodium, potassium, rubidium, cesium, alkaline earth metals such as beryllium, magnesium, calcium, strontium, barium; Metals such as aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium and ytterbium; Two or more of these alloys; Or an alloy of at least one of these with at least one of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten and tin; And it may be a structure comprising at least two of these. The transparent electrode may be, for example, ITO, IZO, ZnO or graphene. The reflective electrode may be formed of, for example, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a compound thereof, and thereafter, ITO, IZO, ZnO, or graphene may be formed thereon. Can be formed by forming a film.

In another embodiment of the organic light emitting diode of the present invention, it may further include at least one of a hole transport layer and a hole injection layer between the anode layer and the light emitting layer. The hole transport layer may preferably include a hole transport material used in the light emitting layer. The hole injection layer may be, for example, a phthalocyanine compound such as copper phthalocyanine, m-MTDATA (4,4 ′, 4 ″ -Tris (3-methylphenylphenylamino) triphenylamine), TDATA (4,4 ′, 4 ″ -tris (N , N-diphenyl-amino) triphenylamine), TAPC (1,1-bis- (4-bis (4-methyl-phenyl) -amino-phenyl) -cyclohexane), 2-TNATA (4,4, 4-tris ( N- (2-naphthyl) -N-phenyl-amino) triphenylamine), Pani / DBSA (polyaniline / dodecylbenzenesulfonic acid), PEDOT / PSS (poly (3,4-ethylenedioxythiophene) / poly (4-styrene Sulfonates)), Pani / CSA (polyaniline / camphorsulfonic acid), Pani / PSS (polyaniline / poly (4-styrenesulfonate)), or mixtures thereof. When both the hole transport layer and the hole injection layer are used, the hole injection layer may be located between the anode layer and the hole transport layer.

In another embodiment of the organic light emitting diode of the present invention, at least one of an electron transport layer and an electron injection layer may be further included between the cathode layer and the light emitting layer. The electron transporting layer may preferably include an electron transporting material used for the light emitting layer. The electron injection layer may include, for example, LiF, NaCl, CsF, Li ₂ O, BaO, or a mixture thereof. When both the electron transport layer and the electron injection layer are used, the electron injection layer may be located between the cathode layer and the electron transport layer.

In another embodiment of the organic light emitting diode of the present invention, the electron transport layer may further include n dopant. The n dopant may be, for example, Rb ₂ CO ₃ , Cs ₂ CO ₃ , LiF, or a mixture thereof. By further including n dopant in the electron transport layer, it is possible to induce charge balance between the electron transport layer and the hole transport layer. The charge balance between the electron transport layer and the hole transport layer may further improve the external quantum efficiency of the organic light emitting diode.

Hereinafter, an example of a method of manufacturing the organic light emitting diode of the present invention will be described in detail (an embodiment in which the anode layer is located at the bottom).

First, an anode layer is formed on a substrate. As a board | substrate, the board | substrate used for a conventional organic light emitting element can be used, The glass substrate or transparent plastic substrate which is excellent in mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproofness can be used. For example, the substrate can be formed of a transparent glass material mainly containing SiO ₂ . The anode layer may be formed using various known methods, for example, a deposition method, a sputtering method or a spin coating method. A hole injection layer is formed on the anode layer. The hole injection layer may be formed on the anode layer using various methods such as vacuum deposition, spin coating, casting, or Langmuir-Blodgett (LB). A hole transport layer is formed on the hole injection layer. The hole transport layer may be formed using various methods such as vacuum deposition, spin coating, casting or LB. An emission layer is formed on the hole transport layer. The light emitting layer may be formed using various methods such as vacuum deposition, spin coating, cast or LB. An electron transport layer is formed on the light emitting layer. The electron transport layer may be formed using various methods such as vacuum deposition, spin coating, casting or LB. An electron injection layer is formed on the electron transport layer. The electron injection layer may be formed using various methods such as vacuum deposition, spin coating, casting or LB. The cathode layer is formed on the electron injection layer. The cathode layer may be formed using various known methods, for example, a deposition method, a sputtering method or a spin coating method.

According to another aspect of the invention, there is provided an illumination comprising the organic light emitting diode of the invention. The illumination is an anode layer; A light emitting layer on the anode layer, the light emitting layer including a dopant comprising a host including a hole transport material and an electron transport material and an Ir (mphmq) ₂ tmd phosphorescent material forming an exciplex; And an anode layer disposed on the emission layer.

According to another aspect of the present invention, there is provided a display device comprising the organic light emitting diode of the present invention. The display device includes a transistor including a source, a drain, a gate, and an active layer; And a light emitting layer including an anode layer, a light emitting layer on the anode layer, a dopant including a host including an hole transport material and an electron transport material to form an exciplex, and an Ir (mphmq) ₂ tmd phosphorescent material. An organic light emitting diode including a cathode layer disposed on the light emitting layer; a cathode layer or an anode layer of the organic light emitting diode may be electrically connected to one of the source and the drain.

Example 1 --- Fabrication of organic light emitting diodes (light emitting layer: NPB, B3PYMPM and Ir (mphmq) ₂ tmd)

On a glass substrate on which ITO 100 nm was deposited, TAPC was deposited at a deposition rate of 1 법 / s at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation to form a hole injection layer having a thickness of 75 nm.

On the hole injection layer, NPB was deposited at a deposition rate of 1 kW / s at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation to form a hole transport layer having a thickness of 10 nm.

Simultaneous deposition of NPB, B3PYMPM and Ir (mphmq) ₂ tmd at 0.49 Å / s, 0.46 Å / s and 0.05 Å / s, respectively, on the hole transport layer at vacuum degrees below 5 x 10 ^-7 torr by vacuum thermal evaporation To form a light emitting layer having a thickness of 30 nm. The molar ratio of NPB: B3PYMPM was 1: 1 and the content of Ir (mphmq) ₂ tmd was 5 wt% based on 100 wt% of the total weight of NPB, B3PYMPM and Ir (mphmq) ₂ tmd.

On the light emitting layer, B3PYMPM was deposited at a deposition rate of 1 kW / s at a vacuum degree of 5 x 10 ^-7 torr or less to form an electron transport layer having a thickness of 10 nm.

To balance charge, simultaneous deposition of RB ₂ CO ₃ as B3PYMPM and n dopant at a deposition rate of 0.98 dl / s and 0.02 dl / s, respectively, on an electron transport layer at a vacuum of 5 x 10 ^-7 torr or less, 45 An electron transport layer for charge balancing was formed. In the charge balancing electron transport layer, the amount of RB ₂ CO ₃ doping was 2 wt% based on 100 wt% of the total weight of B ₃ PYMPM and RB ₂ CO ₃ .

On the charge balancing electron transport layer, the organic light emitting diode of Example 1 was formed by depositing Al to form a 100 nm thick upper electrode at a deposition rate of 4 kW / s at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation. Was prepared.

About the organic light emitting diode of Example 1, the emission spectrum was obtained using the spectrophotometer (Spectrascan PR 650, Photoresearch). 1 is an emission spectrum of the organic light emitting diode of Example 1. FIG. As shown in FIG. 1, the organic light emitting diode of Example 1 showed a peak at 612 nm and may be suitably used as a red light emitting device.

Comparative Example 1 --- Fabrication of organic light emitting diode (Light emitting layer: TCTA, B3PYMPM and Ir (ppy) ₂ acac)

On a glass substrate on which ITO 100 nm was deposited, TAPC was deposited at a deposition rate of 1 kW / s at a vacuum degree of 5 x 10 ^-7 torr or lower by vacuum thermal evaporation to form a hole injection layer having a thickness of 60 nm.

TCTA was deposited on the hole injection layer by vacuum thermal evaporation at a deposition rate of 1 kW / s at a vacuum degree of 5 x 10 ^-7 torr or less to form a 10 nm thick hole transport layer.

Co-deposition of TCTA, B3PYMPM and Ir (ppy) 2acac at 0.52 Å / s, 0.4 Å / s and 0.08 Å / s, respectively, on the hole transport layer at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation To form a light emitting layer having a thickness of 30 nm. The molar ratio of TCTA: B3PYMPM was 1: 1 and the content of Ir (ppy) 2acac was 8 wt% based on 100 wt% of the total weight of TCTA, B3PYMPM and Ir (ppy) 2acac.

TCTA: 4,4 ', 4' '-tris (N-carbazolyl) -triphenylamine

Ir (ppy) 2acac: bis (2-phenylpyridine) iridium (III) acetylacetonate

On the light emitting layer, B3PYMPM was deposited at a deposition rate of 1 증착 / s at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation to form an electron transport layer having a thickness of 40 nm.

On the electron transport layer, LiF was deposited at a deposition rate of 0.01 mW / s at a vacuum degree of 5 x 10 ^-7 torr or lower by vacuum thermal evaporation to form an electron injection layer having a thickness of 0.7 nm.

On the electron injection layer, an organic light emitting diode of Comparative Example 1 was prepared by depositing Al to form an upper electrode having a thickness of 100 nm at a deposition rate of 4 Å / s at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation. It was.

Reference Example 1 --- Formation of Light Emitting Layer

On a glass substrate, NPB, B3PYMPM and Ir (mphmq) 2 tmd were respectively deposited at 0.49 Å / s, 0.46 Å / s and 0.05 Å / s at a vacuum degree of 5 x 10 ^-7 torr by vacuum thermal evaporation. B3PYMPM and Ir (mphmq) 2tmd were simultaneously deposited to form a light emitting layer having a thickness of 30 nm. The molar ratio of NPB: B3PYMPM was 1: 1 and the content of Ir (mphmq) 2tmd was 5 wt% based on 100 wt% of the total weight of NPB, B3PYMPM and Ir (mphmq) 2tmd. The light emitting layer of Reference Example 1 is the same as the light emitting layer used for the organic light emitting diode of Example 1.

Comparative Reference Example 1 --- Formation of Light Emitting Layer

TCTA, B3PYMPM and Ir (ppy) 2acac were deposited at 0.52 판 / s, 0.4 Å / s and 0.08 Å / s, respectively, on a glass substrate at a vacuum degree of 5 x 10 ^-7 torr or less by vacuum thermal evaporation. , B3PYMPM and Ir (ppy) 2acac were simultaneously deposited to form a light emitting layer having a thickness of 30 nm. The molar ratio of TCTA: B3PYMPM was 1: 1 and the content of Ir (ppy) 2acac was 8 wt% based on 100 wt% of the total weight of TCTA, B3PYMPM and Ir (ppy) 2acac. The light emitting layer of Comparative Reference Example 1 is the same as the light emitting layer used in the organic light emitting diode of Comparative Example 1.

Measurement of the horizontal orientation of the phosphor in the light emitting layer

A semi-cylindrical lens made of synthetic quartz is fixed to a sample deposited on a synthetic quartz substrate, and irradiated with a 325 nm laser to emit light. The emitted light passes through a polarizing film and is measured by a photomultiplier tube (PMT) and a monochromator, and rotates by 1 degree and measures from -90 degrees to 90 degrees. Calculate the p-polarized photoluminescence intensity for each angle when the light emitter has a vertical orientation and the p-polarized photoluminescence intensity for each angle that exhibits a horizontal orientation. The orientation rate can be determined.

FIG. 2 is a horizontal orientation measurement result of Ir (mphmq) ₂ tmd phosphor in the light emitting layer of Reference Example 1. FIG. 3 is a result of measuring the horizontal orientation of the Ir (ppy) ₂ acac phosphor in the light emitting layer of Comparative Reference Example 1. FIG. As shown in FIG. 2, the horizontal orientation of the Ir (mphmq) ₂ tmd phosphor in the light emitting layer of Reference Example 1 was 89%. On the other hand, as shown in Figure 3, the horizontal orientation of the Ir (ppy) ₂ acac phosphor in the light emitting layer of Comparative Reference Example 1 was only 76%. From this, it can be seen that the combination of NPB, B3PYMPM and Ir (mphmq) ₂ tmd exerts an unexpected effect of inducing a very good dopant horizontal orientation.

Measurement of External Quantum Efficiency

For the organic light emitting diodes of Example 1 and Comparative Example 1, the relationship between voltage-current density-luminescence brightness was measured using a color research (Photo research spectrophotometer; PR-650) and a power supply (Keithley 2400).

4 is a relationship between voltage, current density, and light emission luminance of the organic light emitting diode of Example 1. FIG. Based on the voltage-current density-luminescence luminance data of FIG. 4, the external quantum efficiency and power efficiency of the organic light emitting diode of Example 1 were calculated. FIG. 5 is a relation between luminance and external quantum efficiency of the organic light emitting diode of Example 1. FIG. FIG. 6 is a relation of power efficiency versus luminance for the organic light emitting diode of Example 1. FIG.

7 is a relationship between voltage, current density, and light emission luminance of the organic light emitting diode of Comparative Example 1. FIG. Based on the voltage-current density-luminescence luminance data of FIG. 7, the external quantum efficiency and power efficiency of the organic light emitting diode of Comparative Example 1 were calculated. 8 is an external quantum efficiency and power efficiency of the organic light emitting diode of Comparative Example 1.

As shown in FIG. 5, the organic light emitting diode of Example 1 had a maximum external quantum efficiency of 37.28%, an external quantum efficiency of 36.92% at a luminance of 1000 nit, and an external quantum efficiency of 31.28% at a luminance of 10000 nit. Such performance is that the organic light emitting diode of Example 1, which exhibits an external quantum efficiency of 30% or more even at high luminance, is the best known in the world. As known to date, the conventional green organic light emitting diode device has a maximum external quantum efficiency of 29%, and the conventional red organic light emitting diode device has a maximum external quantum efficiency of only 26%.

As shown in FIG. 8, the organic light emitting diode of Comparative Example 1 had a maximum external quantum efficiency of 29.1% and an external quantum efficiency of 27.8% at a luminance of 10000 nit. This performance is very poor compared to the organic light emitting diode of Example 1.

From these results, the combination of NPB, B3PYMPM and Ir (mphmq) ₂ tmd for the light emitting layer is unexpected, which "improves the dopant horizontal orientation rate in the light emitting layer and thus the organic light emitting diode has a very improved external quantum efficiency". It can be seen that the effect.

Furthermore, a combination of a hole transport material and an dopant comprising an Ir (mphmq) ₂ tmd phosphorescent material that forms an exciplex for the light emitting layer and an "Im (mphmq) ₂ tmd-based phosphor material, greatly improves the dopant horizontal orientation in the light emitting layer. And accordingly, the organic light emitting diode has a very improved external quantum efficiency. "

Claims

An anode layer;

A light emitting layer on the anode layer, the host including a hole transport material and an electron transport material forming an exciplex; And a dopant comprising an Ir (mphmq) 2 tmd phosphorescent material; And

It includes; a cathode layer located on the light emitting layer,

Organic light emitting diodes.
The method of claim 1, wherein the host is a hole transport material: electron transport material pair for forming an exciplex, NPB: B3PYMPM, TCTA: B3PYMPM, TCTA: TPBi, TCTA: 3TPYMB, TCTA: BmPyPB, TCTA: BSFM, CBP An organic light emitting diode comprising B3PYMPM or NPB: BSFM.
The organic light emitting diode of claim 1, wherein the content of the electron transporting material is 50 to 150 parts by weight based on 100 parts by weight of the hole transporting material.
The method of claim 1, wherein in the light-emitting layer, the Ir (mphmq) 2 content of tmd-based phosphors, the hole transport material, a total weight of 100 wt of the electron transport material and the Ir (mphmq) 2 tmd based phosphor An organic light emitting diode, characterized in that from 1 wt% to 20 wt% based on%.
The organic light emitting diode of claim 1, wherein the organic light emitting diode further comprises at least one of a hole transport layer and a hole injection layer between the anode layer and the light emitting layer.
The organic light emitting diode of claim 1, wherein the organic light emitting diode further comprises at least one of an electron transporting layer and an electron injection layer between the cathode layer and the light emitting layer.
The organic light emitting diode of claim 6, wherein the electron transport layer further comprises n dopant.
An illumination comprising the organic light emitting diode according to any one of claims 1 to 7.
A display device comprising the organic light emitting diode according to any one of claims 1 to 7.